diff --git a/vhdl/arty_a7.vhdl b/vhdl/arty_a7.vhdl
index b9c388a..24a6a46 100644
--- a/vhdl/arty_a7.vhdl
+++ b/vhdl/arty_a7.vhdl
@@ -322,7 +322,17 @@ begin
 
 	pmod_a <= "00" & drivers(5 downto 0);
 	pmod_b <= "00" & drivers(11 downto 6);
-	pmod_c <= "00" & drivers(17 downto 12);
+
+	pmod_c(7) <= '0';
+	pmod_c(6) <= '0';
+	pmod_c(5) <= drivers(17);
+	pmod_c(4) <= drivers(16);
+	pmod_c(3) <= drivers(15);
+	pmod_c(2) <= drivers(14);
+	-- workaround for https://github.com/gatecat/nextpnr-xilinx/issues/42#issuecomment-1183525828
+	pmod_c(1) <= drivers(12);
+	pmod_c(0) <= drivers(13);
+
 	pmod_d <= "00" & drivers(23 downto 18);
 
 	sender: process(sys_clk)